US20240167136A1 - High strength and high plasticity hot-forming steel with oxidation resistance for automobiles and hot-forming process - Google Patents

High strength and high plasticity hot-forming steel with oxidation resistance for automobiles and hot-forming process Download PDF

Info

Publication number
US20240167136A1
US20240167136A1 US18/025,277 US202118025277A US2024167136A1 US 20240167136 A1 US20240167136 A1 US 20240167136A1 US 202118025277 A US202118025277 A US 202118025277A US 2024167136 A1 US2024167136 A1 US 2024167136A1
Authority
US
United States
Prior art keywords
hot
forming
steel
forming steel
strength
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
US18/025,277
Inventor
Yi Dong
Rendong LIU
Xiaoguang SHI
Chengqian SUN
Junxiong Wang
Chufei HAN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Angang Steel Co Ltd
Original Assignee
Angang Steel Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Angang Steel Co Ltd filed Critical Angang Steel Co Ltd
Assigned to ANGANG STEEL COMPANY LIMITED reassignment ANGANG STEEL COMPANY LIMITED ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: DONG, YI, HAN, Chufei, LIU, RENDONG, SHI, Xiaoguang, SUN, Chengqian, WANG, JUNXIONG
Publication of US20240167136A1 publication Critical patent/US20240167136A1/en
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/38—Ferrous alloys, e.g. steel alloys containing chromium with more than 1.5% by weight of manganese
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D—WORKING OR PROCESSING OF SHEET METAL OR METAL TUBES, RODS OR PROFILES WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21D22/00—Shaping without cutting, by stamping, spinning, or deep-drawing
    • B21D22/02—Stamping using rigid devices or tools
    • B21D22/022—Stamping using rigid devices or tools by heating the blank or stamping associated with heat treatment
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/18—Hardening; Quenching with or without subsequent tempering
    • C21D1/19—Hardening; Quenching with or without subsequent tempering by interrupted quenching
    • C21D1/20—Isothermal quenching, e.g. bainitic hardening
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/002—Heat treatment of ferrous alloys containing Cr
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D6/00—Heat treatment of ferrous alloys
    • C21D6/005—Heat treatment of ferrous alloys containing Mn
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/13—Modifying the physical properties of iron or steel by deformation by hot working
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/005—Modifying the physical properties by deformation combined with, or followed by, heat treatment of ferrous alloys
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0226—Hot rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
    • C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
    • C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
    • C21D8/0236—Cold rolling
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/46—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for sheet metals
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/001—Ferrous alloys, e.g. steel alloys containing N
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/22—Ferrous alloys, e.g. steel alloys containing chromium with molybdenum or tungsten
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/24—Ferrous alloys, e.g. steel alloys containing chromium with vanadium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/26—Ferrous alloys, e.g. steel alloys containing chromium with niobium or tantalum
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/28—Ferrous alloys, e.g. steel alloys containing chromium with titanium or zirconium
    • C—CHEMISTRY; METALLURGY
    • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
    • C22C—ALLOYS
    • C22C38/00—Ferrous alloys, e.g. steel alloys
    • C22C38/18—Ferrous alloys, e.g. steel alloys containing chromium
    • C22C38/32—Ferrous alloys, e.g. steel alloys containing chromium with boron
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
    • C21D1/62—Quenching devices
    • C21D1/673—Quenching devices for die quenching
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/001—Austenite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/005—Ferrite
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D2211/00—Microstructure comprising significant phases
    • C21D2211/008—Martensite
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the present invention relates to the technical field of automobile steel, in particularly to a high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles and a hot-forming process thereof.
  • ultra-high strength steel plates for cold stamping at strength levels above 1000 MPa are often used for manufacturing components with simple shapes due to the constraints of easy cracking and large springback.
  • the hot-forming steel is formed in an austenite zone by using hot-forming process, and has small springback, which can meet the requirements of assembly accuracy.
  • the ultra-high strength components of 1500 MPa level and above can be obtained, which effectively simplifies the design of body structure and parts, and greatly reduces the weight of the vehicle.
  • hot-forming steels on the market can be classified as coated hot-forming steels and uncoated hot-forming steels according to their surface conditions.
  • the uncoated steel is easy to form scale on its surface and suffers from decarburization when being heated in a heating furnace, which affects the performance of the steel; therefore, it is necessary to use protective atmosphere during heating of the hot-forming steel, and to make the shot peening treatment after hot forming, which increases the cost and working procedures.
  • the coated steel has an aluminum-silicon coating or zinc-based coating on the surface of the steel plate, which can effectively prevent the steel from surface decarburization and oxidation during heating, and the steel after hot forming can be exempted from the shot peening process, but the cost of the coated hot-forming steel is higher than the uncoated steel.
  • the strengthen level used for mass production and use of the hot-forming steel in the prior art is 1500 MPa; however, the elongation of the hot-forming steel after hot forming is only about 6-9%, and no better technology is available to keep a lower cost of the hot-forming steel, to solve the problem of surface oxidation and decarburization of the steel after hot forming, and to avoid the shot peening process, moreover, the hot-forming steel also has ultra-high strength and good plasticity.
  • the patent with the Publication No. being CN106811689B proposes a method for preparing a hot-forming steel with a tensile strength ⁇ 2000 MPa, the hot-rolled substrate prepared by the method has lower strength and higher elongation, which is beneficial to the shear blanking before hot forming, and the tensile strength of the steel plate after hot forming can reach greater than 2000 MPa, but the Si content in its chemical composition is high, which is not beneficial to obtaining good surface quality.
  • gas protection and shot peening are still required, although the strength of the steel plate after hot forming is high, its elongation is lower than 9%.
  • the patent with Publication No. being CN106119693B proposes a hot-forming steel with a tensile strength ⁇ 2100 MPa directly rolled by thin slab and a production method thereof, after treatments of smelting, hot rolling and hot forming process, the steel plate can reach a tensile strength of being greater than 2100 MPa, but the production process and hot-forming process of the steel plate are controlled by the traditional process, and the elongation of the steel plate after hot forming is lower than 6%, which does not have the performance characteristics of high strength and high plasticity, and does not meet the requirements of the whole process and low-cost process without gas protection and shot blasting.
  • the patent with Publication No. being CN103255340B proposes a high-strength and tough hot-forming steel plate for automobiles and a preparation method thereof.
  • Chemical compositions of the steel sheet include C: 0.1-0.5%, Si: 0.5-1.5%, Mn: 1.2-2.4%, Ti: 0.01-0.05%, B: 0.001-0.005%, S: ⁇ 0.01%, and P: ⁇ 0.01%.
  • the tensile strength of the steel plate reaches 1600 MPa and the elongation reaches 16%, proving good comprehensive performance and relatively low alloy cost.
  • the steel plate needs to be deformed during heating process, and then quenched twice to obtain the final microstructure and mechanical properties, which involves a complicated hot-forming process and is unable to be implemented through the existing equipment, moreover, it also needs gas protection during heating, and needs shot peening after hot forming.
  • the present invention provides a high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles and a hot-forming process thereof.
  • a high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles where the hot-forming steel has chemical compositions in mass percentages as follows: C: 0.35%-0.50%, Si: ⁇ 0.20%, Mn: 1.50%-2.50%, P: 0.050%-0.10%, S ⁇ 0.004%, Als: 0.02%-0.06%, Nb: 0.03%-0.07%, Ti: 0.020%-0.050%, V: 0.08%-0.15%, Cr: 1.50%-3.20%, Mo: 0.10%-0.30%, B: ⁇ 0.0040%, N ⁇ 0.005%, the balance Fe and inevitable impurities.
  • a microstructure of the hot-forming steel includes a ferrite, a martensite and a retained austenite.
  • the ferrite has a volume fraction of 4%-10%, the martensite has a volume fraction of 78%-90%, and the retained austenite has a volume fraction of 6%-12%.
  • the hot-forming steel has an oxidation resistance rate ⁇ 0.1 g/(m 2 ⁇ h), an oxidation resistance up to Level 1, a tensile strength ⁇ 2000 MPa, a yield strength ⁇ 1400 MPa, and an elongation ⁇ 12.0%.
  • the surface of the steel is not completely decarburized with a thickness of decarburized layer ⁇ 15 ⁇ m, and the hot-forming steel has a thickness of 0.8-12.0 mm.
  • Main role of the composition of the hot-forming steel disclosed in the present invention is as follows:
  • the austenitizing temperature is lowered, the hardenability of the steel is improved, and the oxidation of the steel is propitious to be inhibited.
  • the critical cooling rate of the steel after hot forming is reduced, and is beneficial to the production of thick-specification hot-forming steel.
  • a certain content of ferrite can be obtained in the air-cooling stage, and a certain content of retained austenite with good stability can be obtained in the pressure-holding stage after cooling, which improves the plasticity of the steel.
  • Si and P elements in the composition inhibits the precipitation of carbides, which guarantees the content of retained austenite in the steel and improves the mechanical properties of the steel.
  • the Cr and Mo elements in the steel composition play an anti-oxidation role, so that the steel can be heated and kept warm under the condition of having no protective atmosphere, and can be subjected to the subsequent processes after hot forming directly without shot peening.
  • the present invention also discloses a hot-forming process of high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles, including the following steps:
  • the above hot-forming substrate is obtained after smelting, hot rolling and cold rolling.
  • the smelted composition and the mass percentage thereof are the composition and mass percentage of the aforesaid high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles.
  • the steel plate provided in the present invention does not need atmosphere protection during hot forming, does not need shot blasting treatment after hot forming, and can be subjected to the subsequent processes directly, and the whole process cost of the steel plate is lower than that of the existing hot-forming products.
  • the present disclosure has the following advantages:
  • the present invention can be widely popularized in the fields of automobile steel and the like.
  • the present invention provides a high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles, where the hot-forming steel has chemical compositions in mass percentages as follows: C: 0.35%-0.50%, Si: ⁇ 0.20%, Mn: 1.50%-2.50%, P: 0.050%-0.10%, S ⁇ 0.004%, Als: 0.02%-0.06%, Nb: 0.03%-0.07%, Ti: 0.020%-0.050%, V: 0.08%-0.15%, Cr: 1.50%-3.20%, Mo: 0.10%-0.30%, B: ⁇ 0.0040%, N ⁇ 0.005%, the balance Fe and inevitable impurities.
  • a microstructure of the hot-forming steel includes a ferrite, a martensite and a retained austenite.
  • the ferrite has a volume fraction of 4%-10%, the martensite has a volume fraction of 78%-90%, and the retained austenite has a volume fraction of 6%-12%.
  • the hot-forming steel has an oxidation resistance rate ⁇ 0.1 g/(m 2 ⁇ h), an oxidation resistance up to Level 1, a tensile strength ⁇ 2000 MPa, a yield strength ⁇ 1400 MPa, and an elongation ⁇ 12.0%.
  • the surface of the steel is not completely decarburized with a thickness of decarburized layer ⁇ 15 ⁇ m, and the hot-forming steel has a thickness of 0.8-12.0 mm.
  • the high-strength hot-forming steel with excellent oxidation resistance obtained in this embodiment obtains a hot-forming substrate with a thickness of 0.8-12.0 mm. Then, a hot-forming process is performed, and the hot-forming process includes the following steps:
  • compositions, hot-forming process parameters, and the microstructure and performance of the steel after hot forming of the embodiments of the present invention are shown in Tables 1 to 3.
  • Embodiment C Si Mn P S Als Nb V Ti Cr Mo B N 1 0.35 0.20 2.30 0.10 0.003 0.036 0.058 0.15 0.045 3.0 0.20 0.0040 0.003 2 0.37 0.17 2.50 0.092 0.002 0.020 0.070 0.13 0.050 3.2 0.10 0.0033 0.005 3 0.39 0.12 1.90 0.085 0.003 0.035 0.065 0.11 0.040 2.5 0.30 0.0025 0.003 4 0.42 0.05 1.85 0.074 0.002 0.041 0.053 0.10 0.036 2.3 0.15 0.0020 0.002 5 0.44 0.08 1.78 0.065 0.004 0.055 0.045 0.090 0.028 1.80 0.25 0.0015 0.001 6 0.50 0.01 1.50 0.050 0.003 0.060 0.030 0.080 0.020 1.50 0.30 0.0005 0.001 7 0.46 0.10 2.10 0.080 0.020 1.50 0.30 0.0005 0.001 7 0.46 0.10 2.10
  • a hot-forming steel with high-strength and high-plasticity can be obtained, the tensile strength of the steel is ⁇ 2000 MPa, and the elongation reaches or exceeds 12%; by adding Cr, Mo and other elements, the oxidation resistance of the steel is improved, the oxidation resistance rate of the steel is ⁇ 0.1 g/(m 2 ⁇ h), the oxidation resistance level reaches Level 1, and the steel does not need atmosphere protection during hot forming, does not need shot blasting treatment after hot forming, and can be subjected to the subsequent processes directly.
  • the proposed hot-forming steel and hot-forming process is lower in the whole process cost than that of the existing hot-forming products, and can be implemented through the existing equipment, without equipment modification.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Heat Treatment Of Steel (AREA)
  • Heat Treatment Of Sheet Steel (AREA)
  • Heat Treatment Of Articles (AREA)

Abstract

Provided are a high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles and a hot-forming process thereof, and the hot-forming steel has chemical compositions in mass percentages as follows: C: 0.35%-50%, Si: ≤0.20%, Mn: 1.50%-2.50%, P: 0.050%-0.10%, S≤0.004%, Als: 0.02%-0.06%, Nb: 0.03%-0.07%, Ti: 0.020%-0.050%, V: 0.08%-0.15%, Cr: 1.50%-3.20%, Mo: 0.10%-0.30%, B: ≤0.0040%, N≤0.005%, the balance Fe and inevitable impurities. The hot-forming steel provided in the present invention has high oxidation resistance, high strength and plasticity, does not need atmosphere protection during hot forming, and does not need shot blasting treatment after hot forming.

Description

    TECHNICAL FIELD
  • The present invention relates to the technical field of automobile steel, in particularly to a high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles and a hot-forming process thereof.
    • BACKGROUND ART
  • In recent years, new materials for bodywork have been continuously developed and applied to car bodies. However, ultra-high strength steel plates for cold stamping at strength levels above 1000 MPa are often used for manufacturing components with simple shapes due to the constraints of easy cracking and large springback. However, the hot-forming steel is formed in an austenite zone by using hot-forming process, and has small springback, which can meet the requirements of assembly accuracy. Through pressure-holding and quenching, the ultra-high strength components of 1500 MPa level and above can be obtained, which effectively simplifies the design of body structure and parts, and greatly reduces the weight of the vehicle.
  • At present, hot-forming steels on the market can be classified as coated hot-forming steels and uncoated hot-forming steels according to their surface conditions. The uncoated steel is easy to form scale on its surface and suffers from decarburization when being heated in a heating furnace, which affects the performance of the steel; therefore, it is necessary to use protective atmosphere during heating of the hot-forming steel, and to make the shot peening treatment after hot forming, which increases the cost and working procedures. While the coated steel has an aluminum-silicon coating or zinc-based coating on the surface of the steel plate, which can effectively prevent the steel from surface decarburization and oxidation during heating, and the steel after hot forming can be exempted from the shot peening process, but the cost of the coated hot-forming steel is higher than the uncoated steel. At present, the strengthen level used for mass production and use of the hot-forming steel in the prior art is 1500 MPa; however, the elongation of the hot-forming steel after hot forming is only about 6-9%, and no better technology is available to keep a lower cost of the hot-forming steel, to solve the problem of surface oxidation and decarburization of the steel after hot forming, and to avoid the shot peening process, moreover, the hot-forming steel also has ultra-high strength and good plasticity.
  • The patent with the Publication No. being CN106811689B proposes a method for preparing a hot-forming steel with a tensile strength ≥2000 MPa, the hot-rolled substrate prepared by the method has lower strength and higher elongation, which is beneficial to the shear blanking before hot forming, and the tensile strength of the steel plate after hot forming can reach greater than 2000 MPa, but the Si content in its chemical composition is high, which is not beneficial to obtaining good surface quality. Moreover, only the traditional hot-forming process is adopted, gas protection and shot peening are still required, although the strength of the steel plate after hot forming is high, its elongation is lower than 9%.
  • The patent with Publication No. being CN106119693B proposes a hot-forming steel with a tensile strength ≥2100 MPa directly rolled by thin slab and a production method thereof, after treatments of smelting, hot rolling and hot forming process, the steel plate can reach a tensile strength of being greater than 2100 MPa, but the production process and hot-forming process of the steel plate are controlled by the traditional process, and the elongation of the steel plate after hot forming is lower than 6%, which does not have the performance characteristics of high strength and high plasticity, and does not meet the requirements of the whole process and low-cost process without gas protection and shot blasting.
  • The patent with Publication No. being CN103255340B proposes a high-strength and tough hot-forming steel plate for automobiles and a preparation method thereof. Chemical compositions of the steel sheet include C: 0.1-0.5%, Si: 0.5-1.5%, Mn: 1.2-2.4%, Ti: 0.01-0.05%, B: 0.001-0.005%, S: ≤0.01%, and P: ≤0.01%. After hot-forming, the tensile strength of the steel plate reaches 1600 MPa and the elongation reaches 16%, proving good comprehensive performance and relatively low alloy cost. However, the steel plate needs to be deformed during heating process, and then quenched twice to obtain the final microstructure and mechanical properties, which involves a complicated hot-forming process and is unable to be implemented through the existing equipment, moreover, it also needs gas protection during heating, and needs shot peening after hot forming.
  • To sum up, the development of high strength and high plasticity hot-forming process with good oxidation resistance and the hot forming technology for automobiles has good application prospects.
    • SUMMARY
  • According to the above technical problems, the present invention provides a high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles and a hot-forming process thereof.
  • A technical solution adopted by the present invention is as follows:
  • A high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles, where the hot-forming steel has chemical compositions in mass percentages as follows: C: 0.35%-0.50%, Si: ≤0.20%, Mn: 1.50%-2.50%, P: 0.050%-0.10%, S≤0.004%, Als: 0.02%-0.06%, Nb: 0.03%-0.07%, Ti: 0.020%-0.050%, V: 0.08%-0.15%, Cr: 1.50%-3.20%, Mo: 0.10%-0.30%, B: ≤0.0040%, N≤0.005%, the balance Fe and inevitable impurities.
  • A microstructure of the hot-forming steel includes a ferrite, a martensite and a retained austenite.
  • The ferrite has a volume fraction of 4%-10%, the martensite has a volume fraction of 78%-90%, and the retained austenite has a volume fraction of 6%-12%.
  • The hot-forming steel has an oxidation resistance rate ≤0.1 g/(m2·h), an oxidation resistance up to Level 1, a tensile strength ≥2000 MPa, a yield strength ≥1400 MPa, and an elongation ≥12.0%. The surface of the steel is not completely decarburized with a thickness of decarburized layer ≤15 μm, and the hot-forming steel has a thickness of 0.8-12.0 mm.
  • Main role of the composition of the hot-forming steel disclosed in the present invention is as follows:
      • C: C is the guarantee of steel strength, which is beneficial to improving hardenability of the steel. If the carbon content is too low, the strength of the steel after hot stamping cannot reach the expected target. If the carbon content is too high, the strength of the steel after hot forming will be too high, and the plasticity will thus decrease. In addition, the increase of C content can reduce the phase transition temperature, so the austenitizing temperature of the steel will be lowered, which is beneficial to obtaining a shot blasting-free surface. At the same time, the increase of C content is beneficial to generating sufficient content of undercooled austenite during pressure holding of the hot-forming process and to improving the plasticity. Therefore, the optimal range of C in the present invention is 0.35%-0.50%.
      • Si: Si is an element without carbide precipitation in steel, which has a good inhibiting effect on carbide precipitation during cooling and pressure holding of the hot-forming process, thereby ensuring the content and stability of retained austenite. However, if the Si content is too high, a large number of defects such as scale and color difference will appear on the surface of the hot-forming substrate, which will affect the surface quality of hot-forming parts. At the same time, too high Si content will enlarge the two-phase region, raise the austenitizing temperature, and make the steel keep warm at a higher temperature, which is easy to deteriorate the surface of the steel. Therefore, the Si content proposed in the present invention is ≤0.20%.
      • Mn: Main role of Mn in this hot-forming steel is to improve the hardenability of the steel and reduce the phase transition temperature, so that the austenitization of the steel can be realized at a lower temperature. Too high content of Mn will deteriorate the microstructure uniformity of the steel, and easily cause serious banded structural defects in the microstructure. Therefore, the selected Mn content in the present invention is 1.50%-2.50%.
      • P: P can inhibit the formation of cementite and improve the stability of retained austenite, the role of which is similar to that of Si in this hot-forming steel. Also, P can have martensite laths refined, distribute it evenly and improve the toughness. The P content in the present invention is 0.050%-0.10%.
      • S: S is a harmful element in this hot-forming steel, and S will form MnS inclusions, which will deteriorate the microstructure and mechanical properties of the steel. Therefore, S is limited to ≤0.004% in the present invention.
      • Als: Als (acid-soluble aluminum) plays a role of deoxidization and nitrogen fixation in the smelting process, but too much Als will give rise to a large number of aluminum-based inclusions. The Als content in the present invention is 0.020%-0.060%.
      • Cr: Cr is an element for improving the hardenability of the steel. In the present invention, main role of Cr is to improve the high-temperature oxidation resistance of the steel and simultaneously improve the tempering stability of the steel, so as to ensure that the steel does not appear tempered martensite within the pressure-holding temperature range. The optimum Cr content falls between 1.50% and 3.20%.
      • Mo: Mo is a medium-strong carbide forming element that can improve the strength and toughness of the steel. In the present invention, Mo can lower the martensitic transformation temperature, significantly improve the stability of retained austenite, and at the same time, the addition of Mo element improves the oxidation resistance of the steel. The Mo content in the present invention is 0.10%-0.30%.
      • Nb, V: Nb and V mainly play the role of fine grain strengthening and precipitation strengthening in steel. In the present invention, Nb and V can effectively pin the original austenite grain boundary by diffusely precipitating the nano-scale fine carbides, thereby refining the structure of each phase in the hot-forming steel and improving the comprehensive performance. At the same time, the diffusely precipitated carbides can act as hydrogen traps to pin the diffusible hydrogen in the steel, which can improve the delayed fracture resistance of the steel. In addition, VN precipitation formed by V and N can inhibit BN precipitation and avoid the strength reduction caused by B precipitation. In the present invention, the Nb content is 0.030%-0.070%, and the V content is 0.080%-0.15%.
      • Ti: Ti is mainly used for fixing nitrogen in boron steel to ensure that the quenching effect of boron can be exerted. In addition, Ti can also form fine carbide precipitation with C element, which reduces the hardness and strength of martensite in the structure after hot forming, and is beneficial to improving the plasticity and toughness of the steel. The Ti content in the present invention falls between 0.020% and 0.050%.
      • B: Adding boron to the steel can significantly improve the hardenability of the steel and ensure the stability of steel strength after quenching. Too high B content is easy to form B compounds with N in the steel, which will reduce the performance of the steel. Therefore, the B content in the present invention is ≤0.0040%.
      • N: The lower the N content is, the better it becomes, but too low content of N will lead to production difficulties and increase the cost, so the N content in the present invention is ≤0.005%.
  • In the present invention, by adding alloying elements such as C, Mn, Cr, Mo, etc., the austenitizing temperature is lowered, the hardenability of the steel is improved, and the oxidation of the steel is propitious to be inhibited. At the same time, the critical cooling rate of the steel after hot forming is reduced, and is beneficial to the production of thick-specification hot-forming steel. In addition, through the combination of chemical composition and hot forming process, a certain content of ferrite can be obtained in the air-cooling stage, and a certain content of retained austenite with good stability can be obtained in the pressure-holding stage after cooling, which improves the plasticity of the steel. The addition of Si and P elements in the composition inhibits the precipitation of carbides, which guarantees the content of retained austenite in the steel and improves the mechanical properties of the steel. In addition, the Cr and Mo elements in the steel composition play an anti-oxidation role, so that the steel can be heated and kept warm under the condition of having no protective atmosphere, and can be subjected to the subsequent processes after hot forming directly without shot peening.
  • The present invention also discloses a hot-forming process of high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles, including the following steps:
      • (1) Placing the hot-forming substrate containing the above compositions into a heating furnace at a temperature of AC3-AC3+30° C. for heating and heat preservation for a period of 180 s-300 s, and the step is implemented to make the hot-forming substrate completely austenitic and make it have smaller original austenitic grain size; at the same time, lower austenitizing temperature is beneficial to reducing the surface oxidation of the hot-forming substrate;
      • (2) taking the heated hot-forming steel out of the heating furnace for air cooling to a temperature of Ara and staying for 3 s-5 s before being put into a hot-forming mold for deformation and cooling, at a cooling rate of ≥10° C./s, performing the pressure holding for 60 s-90 s after cooling to 250° C.-300° C., and taking out the formed parts for air-cooling to room temperature after pressure holding to obtain the hot-forming steel.
  • The above hot-forming substrate is obtained after smelting, hot rolling and cold rolling. The smelted composition and the mass percentage thereof are the composition and mass percentage of the aforesaid high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles.
  • The steel plate provided in the present invention does not need atmosphere protection during hot forming, does not need shot blasting treatment after hot forming, and can be subjected to the subsequent processes directly, and the whole process cost of the steel plate is lower than that of the existing hot-forming products.
  • Compared with the prior art, the present disclosure has the following advantages:
      • (1) through the combination of chemical composition and hot forming process provided in the present invention, a hot-forming steel with high-strength and high-plasticity can be obtained, the tensile strength of the steel is ≥2000 MPa, and the elongation reaches or exceeds 12%;
      • (2) by adding Cr element, the high temperature oxidation resistance of the steel is improved, the oxidation resistance rate of the steel is ≤0.1 g/(m2·h), the oxidation resistance level reaches Level 1, and the steel does not need atmosphere protection during hot forming, does not need shot blasting treatment after hot forming and can be subjected to the subsequent processes directly; and
      • (3) the proposed hot-forming steel and hot-forming process can be implemented through the existing equipment, without equipment modification and at a relatively low cost.
  • Based on the above reasons, the present invention can be widely popularized in the fields of automobile steel and the like.
    • DETAILED DESCRIPTION OF THE EMBODIMENTS
  • It should be noted that the embodiments of the present invention and features in the embodiments, under the condition of no conflict, can be combined with each other. The described embodiments are some, rather than all of the embodiments of the present disclosure. The following description of at least one example embodiment is merely illustrative in nature, and is in no way intended to limit the present disclosure, an application or use thereof. Based on the embodiments of the present disclosure, all other embodiments acquired by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present disclosure
  • The present invention provides a high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles, where the hot-forming steel has chemical compositions in mass percentages as follows: C: 0.35%-0.50%, Si: ≤0.20%, Mn: 1.50%-2.50%, P: 0.050%-0.10%, S≤0.004%, Als: 0.02%-0.06%, Nb: 0.03%-0.07%, Ti: 0.020%-0.050%, V: 0.08%-0.15%, Cr: 1.50%-3.20%, Mo: 0.10%-0.30%, B: ≤0.0040%, N≤0.005%, the balance Fe and inevitable impurities.
  • A microstructure of the hot-forming steel includes a ferrite, a martensite and a retained austenite.
  • The ferrite has a volume fraction of 4%-10%, the martensite has a volume fraction of 78%-90%, and the retained austenite has a volume fraction of 6%-12%.
  • The hot-forming steel has an oxidation resistance rate ≤0.1 g/(m2·h), an oxidation resistance up to Level 1, a tensile strength ≥2000 MPa, a yield strength ≥1400 MPa, and an elongation ≥12.0%. The surface of the steel is not completely decarburized with a thickness of decarburized layer ≤15 μm, and the hot-forming steel has a thickness of 0.8-12.0 mm.
  • After smelting, hot rolling and cold rolling, the high-strength hot-forming steel with excellent oxidation resistance provided in this embodiment obtains a hot-forming substrate with a thickness of 0.8-12.0 mm. Then, a hot-forming process is performed, and the hot-forming process includes the following steps:
      • (1) the hot-forming substrate containing the above compositions is placed into a heating furnace at a temperature of AC3-AC3+30° C. for heating and heat preservation for a period of 180 s-300 s, and the step is implemented to make the hot-forming substrate completely austenitic and make it have smaller original austenitic grain size; at the same time, lower austenitizing temperature is beneficial to reducing the surface oxidation of the hot-forming substrate; and
      • (2) the heated hot-forming steel is taken out of the heating furnace for air cooling to a temperature of Ara and stayed for 3 s-5 s before being put into a hot-forming mold for deformation and cooling, at a cooling rate of ≥10° C./s, the pressure holding is performed for 60 s-90 s after cooling to 250° C.-300° C., and the formed parts is taken out for air cooling to room temperature after pressure holding to obtain the hot-forming steel.
  • The compositions, hot-forming process parameters, and the microstructure and performance of the steel after hot forming of the embodiments of the present invention are shown in Tables 1 to 3.
  • TABLE 1
    Composition of Embodiment of the Present Invention (wt, %)
    Embodiment C Si Mn P S Als Nb V Ti Cr Mo B N
    1 0.35 0.20 2.30 0.10 0.003 0.036 0.058 0.15 0.045 3.0 0.20 0.0040 0.003
    2 0.37 0.17 2.50 0.092 0.002 0.020 0.070 0.13 0.050 3.2 0.10 0.0033 0.005
    3 0.39 0.12 1.90 0.085 0.003 0.035 0.065 0.11 0.040 2.5 0.30 0.0025 0.003
    4 0.42 0.05 1.85 0.074 0.002 0.041 0.053 0.10 0.036 2.3 0.15 0.0020 0.002
    5 0.44 0.08 1.78 0.065 0.004 0.055 0.045 0.090 0.028 1.80 0.25 0.0015 0.001
    6 0.50 0.01 1.50 0.050 0.003 0.060 0.030 0.080 0.020 1.50 0.30 0.0005 0.001
    7 0.46 0.10 2.10 0.080 0.003 0.032 0.040 0.14 0.030 2.8 0.25 0.0030 0.002
    8 0.40 0.05 1.60 0.055 0.001 0.023 0.060 0.095 0.033 2.0 0.28 0.0001 0.002
  • TABLE 2
    Hot-forming Process of Embodiment of the Present Invention
    Heat Resi- Pres- Pres-
    Pre- dence sure- sure-
    Heating serva- Time of Cool- holding hold-
    Em- Temper- tion temper- ing Temper- ing
    bodi- AC3, ature, Period, ature Rate, ature, Time,
    ment ° C. ° C. s Ar3, s ° C./s ° C. s
    1 821 850 180 5 25 300 90
    2 811 840 220 4 23 280 80
    3 809 835 250 3 20 260 75
    4 796 825 190 4 17 250 60
    5 796 825 280 5 11 270 70
    6 785 815 300 3 10 265 85
    7 799 825 260 4 16 285 65
    8 803 830 290 5 17 275 78
  • TABLE 3
    Microstructure and performance parameters of Embodiment of the Present Invention
    Oxida- Thick-
    Volume Volume tion ness
    A Volume fraction fraction resist- of
    (elon- fraction of of ance decar-
    Em- Thick- Yield Tensile ga- of marten- auste- rate, burized
    bodi- ness, strength, strength, tion), ferrite, site, nite, g/ layer,
    ment mm MPa MPa % % % % (m2 · h) μm)
    1 0.8 1400 2010 20.5 10 78 12 0.10 9
    2 1.2 1530 2030 18.0 7 86 7 0.07 13
    3 1.4 1460 2045 15.5 9 83 8 0.06 7
    4 7.0 1650 2060 16.5 8 83 9 0.05 13
    5 12.0 1550 2080 14.0 5 85 10 0.06 15
    6 10.0 1680 2120 13.0 4 90 6 0.03 4
    7 2.0 1480 2070 17.5 7 85 8 0.09 11
    8 5.0 1710 2180 12.0 5 86 9 0.08 2
  • Through the combination of new chemical composition and hot forming process provided in the embodiment of the present invention, a hot-forming steel with high-strength and high-plasticity can be obtained, the tensile strength of the steel is ≥2000 MPa, and the elongation reaches or exceeds 12%; by adding Cr, Mo and other elements, the oxidation resistance of the steel is improved, the oxidation resistance rate of the steel is ≤0.1 g/(m2·h), the oxidation resistance level reaches Level 1, and the steel does not need atmosphere protection during hot forming, does not need shot blasting treatment after hot forming, and can be subjected to the subsequent processes directly. Moreover, the proposed hot-forming steel and hot-forming process is lower in the whole process cost than that of the existing hot-forming products, and can be implemented through the existing equipment, without equipment modification.
  • At last, it should be noted that the above various embodiments are merely intended to illustrate the technical solution of the present disclosure and not to limit the same; although the present disclosure has been described in detail with reference to the foregoing embodiments, it should be understood by those ordinary skilled in the art that the technical solutions described in the foregoing embodiments may be modified or equivalents may be substituted for some or all of the technical features thereof; and the modification or substitution does not make the essence of the corresponding technical solution deviate from the scope of the technical solution of each embodiment of the present disclosure.

Claims (10)

1. A high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles, wherein the hot-forming steel has chemical compositions in mass percentages as follows: C: 0.35%-0.50%, Si: ≤0.20%, Mn: 1.50%-2.50%, P: 0.050%-0.10%, S≤0.004%, Als: 0.02%-0.06%, Nb: 0.03%-0.07%, Ti: 0.020%-0.050%, V: 0.08%-0.15%, Cr: 1.50%-3.20%, Mo: 0.10%-0.30%, B: ≤0.0040%, N≤0.005%, the balance Fe and inevitable impurities.
2. The high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles according to claim 1, wherein a microstructure of the hot-forming steel includes a ferrite, a martensite and a retained austenite.
3. The high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles according to claim 2, wherein the ferrite has a volume fraction of 4%-10%, the martensite has a volume fraction of 78%-90%, and the retained austenite has a volume fraction of 6%-12%.
4. The high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles according to claim 1, wherein the tensile strength of the hot-forming steel is 2000 MPa.
5. The high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles according to claim 1, wherein the oxidation resistance rate of the hot-forming steel is ≤0.1 g/(m2·h).
6. The high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles according to claim 1, wherein the yield strength of the hot-forming steel is 1400 MPa.
7. The high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles according to claim 1, wherein the elongation of the hot-forming steel is ≥12.0%.
8. The high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles according to claim 1, wherein the surface of the hot-forming steel is not completely decarburized with a thickness of decarburized layer ≤15 μm.
9. The high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles according to claim 1, wherein the thickness of the hot-forming steel is 0.8 mm-12.0 mm;
10. A hot-forming process of high-strength and high-plasticity hot-forming steel with oxidation resistance for automobiles, comprising:
(1) placing the hot-forming substrate containing the compositions according to claim 1 into a heating furnace at a temperature of AC3-AC3+30° C. for heating and heat preservation for a period of 180 s-300 s; and
(2) taking the heated hot-forming steel out of the heating furnace for air cooling to a temperature of Ara and staying for 3 s-5 s before being put into a hot-forming mold for deformation and cooling, at a cooling rate of ≥10° C./s, performing the pressure holding for 60 s-90 s after cooling to 250° C.-300° C., and taking out the formed parts for air cooling to room temperature after pressure holding to obtain the hot-forming steel.
US18/025,277 2021-11-19 2021-11-25 High strength and high plasticity hot-forming steel with oxidation resistance for automobiles and hot-forming process Pending US20240167136A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
CN202111401625.5 2021-11-19
CN202111401625.5A CN114045440B (en) 2021-11-19 2021-11-19 High-strength high-plasticity hot forming steel with oxidation resistance for automobile and hot forming process
PCT/CN2021/132954 WO2023087351A1 (en) 2021-11-19 2021-11-25 High-strength and high-plasticity thermoformed steel having oxidation resistance for automobile, and thermoforming process

Publications (1)

Publication Number Publication Date
US20240167136A1 true US20240167136A1 (en) 2024-05-23

Family

ID=80210786

Family Applications (1)

Application Number Title Priority Date Filing Date
US18/025,277 Pending US20240167136A1 (en) 2021-11-19 2021-11-25 High strength and high plasticity hot-forming steel with oxidation resistance for automobiles and hot-forming process

Country Status (6)

Country Link
US (1) US20240167136A1 (en)
EP (1) EP4215635A4 (en)
JP (1) JP2024505318A (en)
KR (1) KR20230074701A (en)
CN (1) CN114045440B (en)
WO (1) WO2023087351A1 (en)

Family Cites Families (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4306078B2 (en) * 2000-02-15 2009-07-29 Ｊｆｅスチール株式会社 High tensile hot-rolled steel sheet excellent in bake hardenability and impact resistance and method for producing the same
CN103805840B (en) * 2012-11-15 2016-12-21 宝山钢铁股份有限公司 A kind of high formability galvanizing ultrahigh-strength steel plates and manufacture method thereof
CN103255340B (en) 2012-12-28 2015-08-05 中北大学 A kind of automobile high-strong toughness thermoforming steel plate and preparation method thereof
CN103614640B (en) * 2013-12-12 2016-10-05 马鸣图 A kind of non-coating hot press-formed steel of resistance to high temperature oxidation
CN106119694B (en) * 2016-08-24 2018-01-23 武汉钢铁有限公司 With the tensile strength >=1900MPa hot formings steel and production method of medium thin slab Direct Rolling
CN106119693B (en) * 2016-08-24 2018-01-12 武汉钢铁有限公司 With the thin hot forming steel of tensile strength >=2100MPa of sheet billet Direct Rolling and production method
CN106086684B (en) * 2016-08-24 2018-01-12 武汉钢铁有限公司 With the thin hot forming steel of tensile strength >=1900MPa of sheet billet Direct Rolling and production method
KR101879104B1 (en) * 2016-12-23 2018-07-16 주식회사 포스코 Al-Fe ALLOY PLATED STEEL SHEET FOR HOT PRESS FORMING HAVING EXCELLENT TAILOR-WELDED-BLANK WELDING PROPERTY, HOT PRESS FORMED PART, AND METHOD OF MANUFACTURING THE SAME
CN106811689B (en) * 2017-01-17 2018-02-09 北京科技大学 A kind of preparation method of tensile strength >=2000MPa hot forming steel
CN108642373A (en) * 2018-04-18 2018-10-12 江苏理工学院 A kind of high-temperature oxidation resistant austenitic heat-resistance steel and its preparation process
CN108374127A (en) * 2018-04-28 2018-08-07 育材堂（苏州）材料科技有限公司 Hot press-formed steel, hot press-formed technique and hot press-formed component
CN109972061A (en) * 2019-04-26 2019-07-05 北京科技大学 It is hot press-formed with anti-oxidant ultra-high strength steel plate and its low temperature heat forming technology
CN111893377B (en) * 2020-07-13 2021-10-26 首钢集团有限公司 Aluminum-silicon plated steel plate for 1900 MPa-grade high-strength and high-toughness hot stamping and preparation method thereof
CN111926248B (en) * 2020-07-14 2021-11-30 辽宁科技学院 Ce alloy-added hot stamping forming steel and hot stamping forming process
CN113106338B (en) * 2021-03-22 2022-02-11 北京科技大学 Preparation method of ultrahigh-strength high-plasticity hot stamping formed steel
CN113388773B (en) * 2021-05-21 2022-07-22 鞍钢股份有限公司 1.5GPa grade high-formability hydrogen-embrittlement-resistant ultrahigh-strength automobile steel and preparation method thereof

Also Published As

Publication number Publication date
JP2024505318A (en) 2024-02-06
CN114045440B (en) 2023-03-03
CN114045440A (en) 2022-02-15
EP4215635A1 (en) 2023-07-26
EP4215635A4 (en) 2024-06-26
KR20230074701A (en) 2023-05-31
WO2023087351A1 (en) 2023-05-25

Similar Documents

Publication Publication Date Title
JP6475861B2 (en) Steel plates used for hot stamping, hot stamping process and hot stamping components
KR102470965B1 (en) Steel sheet having excellent toughness, ductility and strength, and manufacturing method thereof
US10577671B2 (en) High-hardness hot-rolled steel product, and a method of manufacturing the same
US9534268B2 (en) Method for manufacturing a hot press-hardened component and use of a steel product for manufacturing a hot press-hardened component
US20240271260A1 (en) High plasticity hot-forming steel with oxidation resistance for automobiles and hot-forming process
CN114369768A (en) Steel material for hot press forming, hot press forming process, and formed member
CN113403549A (en) 1.2 GPa-grade fatigue-resistant high-formability ultrahigh-strength automobile steel and preparation method thereof
CN112195412B (en) Nb-V microalloyed high-strength high-toughness bainite non-quenched and tempered steel for high-power engine crankshaft and preparation method thereof
CN103614640A (en) High-temperature oxidation-resistant steel for non-coating hot stamping
CN107747039A (en) A kind of high reaming performance cold-rolled biphase steel and preparation method thereof
CN116334489A (en) Hot stamping forming steel with super-strong high-temperature oxidation resistance and preparation method thereof
CN113930671A (en) Steel plate for thick-specification high-strength high-toughness structure and preparation method thereof
CN113802065B (en) Hot press-formed member, steel sheet for hot press forming, and hot press process
CN107761007A (en) Strong dual phase steel of low-carbon cold rolling superelevation and preparation method thereof
CN108950150A (en) Manganese Q&P steel heat treatment process in superhigh intensity cold rolling based on complete austenitizing
CN114934228B (en) Hot-formed steel plate and production method thereof
CN114990434B (en) Hot-formed steel material and method for producing same
CN114196875B (en) Stainless steel for valve plate and heat treatment method thereof
US20240167136A1 (en) High strength and high plasticity hot-forming steel with oxidation resistance for automobiles and hot-forming process
WO2012172185A1 (en) Method for manufacturing a medium carbon steel product and a hot rolled medium carbon steel product
CN115261717A (en) 1800 MPa-grade high-strength self-strength and self-toughness steel plate for protection and manufacturing method thereof
JP4175933B2 (en) Nitride steel parts capable of obtaining high surface hardness and deep hardening depth by nitriding for a short time and method for producing the same
CN113930675B (en) 2200 MPa-grade low-carbon B-free hot forming steel and preparation method thereof
RU2812417C1 (en) Method for producing high-strength steel sheet
CN117488180A (en) Ultrahigh-strength structural steel and production method thereof

Legal Events

Date Code Title Description
AS Assignment

Owner name: ANGANG STEEL COMPANY LIMITED, CHINA

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:DONG, YI;LIU, RENDONG;SHI, XIAOGUANG;AND OTHERS;REEL/FRAME:062984/0617

Effective date: 20230217

STPP Information on status: patent application and granting procedure in general

Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION